1. Field
The presently disclosed subject matter relates generally to surgical instrumentation and related methods, and more specifically to ratchet tools for applying torque to a surgical tool, surgical implement, implant or other device used during a surgical procedure or other procedures requiring a torque.
2. Description of the Related Art
There are several occasions in the surgical field that call for the use of a ratchet tool. Typically, a ratchet tool is desired when torque is being applied to another tool, implant, or other surgical device, and the space defining the surgical field is limited. Additionally, ratchet tools are sometimes helpful to decrease the time necessary for completing a particular action or procedure. For example, a ratchet tool can be used to avoid continual removal and reinstallation of a typical standard set wrench.
Known ratchet tools include those used with bone screws, drivers, persuaders, and other structures that require application of torque during surgery. Typically, known ratchet tools are similar to those found in any automotive repair garage. Specifically, known ratchet tools usually include a cylinder that houses a raceway including bearings and a ratchet/pawl mechanism that is biased by a spring. Thus, typical ratchet tools include a number of individual parts that are manufactured or machined, and which are then assembled together to form the ratchet tool. Many ratchet tools include bearings and bearing surfaces, and some have a lubricant that facilitates rotation and relative movement between the separate parts of the known ratchet tool.
It is sometimes crucial for surgeons to monitor a bone screw, spinal rod, or other device as it is being driven into or moved relative to a bone or other tissue. Surgeons typically avoid overtightening or excessively moving the screw or rod, etc., because such an action may cause damage to the bone, tissue, or misalignment of the bone and/or tissue, etc. When surgeons insert and tighten bone screws, rods, etc., via an extender type mechanism, such as a downtube, it may be difficult to visually monitor the screw, rod, or other device to know if it is being overtightened or misaligned. Therefore, surgeons often rely on “feel” or tactile feedback to monitor their progress in driving the screw, rod, or other device for movement or placement relative to a bone or other tissue. Thus, the surgical instrument that is driven is typically rigidly attached to a downtube (or other extender mechanism) in a way that minimizes or prevents “play” or toggle between the driver and downtube. Even a small amount of toggle between the driver and downtube can prevent a surgeon from sensing tactile feedback during a procedure. Thus, the tolerance and fit for the ratchet tool with respect to the surgical instrument, implant or device it is driving is also an important aspect of ensuring that “play” or toggle is minimized during the surgical procedure.
Characteristics and drawbacks of known ratchet tools include a complicated assembly and manufacture process, resulting in a relatively expensive device/tool in terms of both manufacturing cost and parts/material cost. In addition, known ratchet tools are often difficult to sterilize due to their complicated structure. In some cases, the ratchet tool has poor fit and has multiple stationary teeth that move in and out of engagement during ratcheting operation, resulting in play or toggle which has the complications as outlined above.